Re: makefs alignment issue

Eric Sandeen
2014-10-24T20:14:57Z

On 10/24/14 3:11 PM, Stan Hoeppner wrote:
> Just remade a couple of filesystems and received an alignment msg I
> don't recall receiving previously:
>
> # mkfs.xfs -f -d su=64k,sw=12 /dev/s2d_a1l003
> mkfs.xfs: Specified data stripe width 1536 is not the same as the volume
> stripe width 2048

so specified geometry that differs from the underlying device...

> meta-data=/dev/s2d_a1l003 isize=256 agcount=44,
> agsize=268435440 blks
> = sectsz=512 attr=2, projid32bit=0
> data = bsize=4096 blocks=11709285376, imaxpct=5
> = sunit=16 swidth=192 blks
> naming =version 2 bsize=4096 ascii-ci=0
> log =internal log bsize=4096 blocks=521728, version=2
> = sectsz=512 sunit=16 blks, lazy-count=1
> realtime =none extsz=4096 blocks=0, rtextents=0
>
>
> /dev/s2d_a1l003 is an alias to dm-0 which is a dm-multipath device to a
> LUN on hardware RAID. The hardware geometry is 64kx 12, 768k. AFAIK no
> geometry information has been specified for these device mapper devices
> (someone else's responsibility). Though I assume dm geometry data is
> the reason for mkfs.xfs throwing this alert. I don't find anything in
> /sys/devices/virtual/block/dm-0/ indicating geometry.
>
> Any ideas how to verify what's going on here and fix it?

# blockdev --getiomin --getioopt /dev/s2d_a1l003

The first number, minimum io size, is what is used for sunit
The 2nd number, optimal io size, is what is used for swidth

Where dm got the geometry, I'm not sure - you'd have to look into
how you set up the dm device, and what its defaults are I think.

-Eric